Tape control transmitter



Dec. 12, 1961 E. F. KLElNscHMIDT 3,013,118

TAPE CONTROL TRANSMITTER Original Filed Dec. 21, 1953 3 Sheets-Sheet 1 mijn!! Ir, l j' INVENTOR.l EDWARD E KLEINSCHMIDT mj ATTORNEYS Dec. 12, 1961 E. F. KLExNscHMlDT 3,013,118

TAPE CONTROL TRANSMITTER 3 Sheets-Sheet 2 Original Filed Dec.

QS NS IN VEN TOR.

Q al

ATTORNEYS Dec. 12, 1961 E. F. KLEINSCHMIDT TAPE CONTROL TRANSMITTER Original Filed Deo. 2l, 1953 3 Sheets-Sheet 3 @MWL ulg .S SEQ ummm MEE.

m95 waz Si Sz mez Sz Ew met, bez

Amas @srl BBE EN `b...\.. M M @www Ro, bewwbvw BQE; Mii Q Sm QR. een RQ 3N SN QS ab S en e @S QQ QS om o@ am United States Patent() 3,013,1IS TAPE CQNTRL TRNSD'IIT'IER Edward F. Kieinsehmidt, Wilmette, Iii., assigner to niih-Corona Merchant Inc., a corporation ot' New or t @riginal application Bec. 21, 1953, Ser. No. 399,543, now Patent No. 2,923,7653, dated Feb. 2, 196i?. Divided and this application .lune 5, 1959, Ser. No. 818,351 6 Claims. (Cl. 178-17) The present invention relates to telegraph transmitting apparatus and more particularly to perforated tape controlled transmitting devices and is divided from copending application Serial No. 399,548 tiled December 2l, 1953, now U.S. Patent No. 2,923,769, issued February 2, 1960.

The tape transmitter is a self contained unit capable of transmitting teletypewriter signals at more than 600 operations per minute. It will operate with tape perforated by an associated typing tape reperforator or with standard UAG inch perforated tape. It may be removed from its associated reperforator and used alone, or combined with other similar units in a ganging arrangement to form multiple transmitters having a common drive.

The message tape passes over a feed guide against which it is held by a tape guide cover. Five sensing levers are cam operated by means of a bail to be raised and lowered in a timed relationship with a tape feed claw. A sensing lever entering a code hole in the message tape blocks the spacing end of its associated selector lever thus causing the marking end of the lever to move the marking end of a Contact bail to close a marking contact. If the sensing lever does not enter a hole when it is raised it will bear against the underside of the tape and its associated lever will not be blocked, causing a spacing contact to close. The message tape is fed step-bystep in the tape guide over the sensing levers by a fecd claw. Motion is imparted to the feed claw by two cam and spring actuated levers. One lever causes the claws to engage the tape and withdraw after feeding and the other lever moves the claw back and forth a distance of one space. The aggregate motion of the feed claw is substantially rectangular. The camshaft is frictionally driven by a motor and is start-stop controlled by a magnet armature. The magnet circuit is controlled by several switches which include a manual on-oi switch; an ende o-tape switch and a tight-tape switch. The end-of-tape switch is closed only when tape is present under the tape guide cover, and the tight-tape switch is closed only when suilicient slack is present between the transmitter and its supply source.

A primary object of this invention resides in the provision of novel coded tape sensing mechanism and coordinated mechanism for converting the coded tape representations to electrical signal line conditions through a contact assembly.

Another object resides in the provision of a perforated tape controlled transmitting mechanism with transmitting switch contacts, means to sense and feed the perforated tape and coordinated means to conver the mechanically sensed tape signal into mechanical switch contact coded actuations.

Further novel features and other objects of this invention will become apparent from the following detailed description, discussion and the appended claims taken in conjunction with the accompanying drawings showing a preferred structure and embodiment, in which:

FIGURE l is a cutaway perspective view of the transmitter assembly;

FIGURE 2 is a front elevational view of the tape feeding mechanism apart from the sensing mechanism;

FIGURE 3 is a detailed view of the tape sensing mechanism apart from the feeding mechanism;

FIGURE 4 is a detailed view of the transmitting con tacts and their associated operating mechanism;

FIGURE 5 is a top view of the tape feed gate;

FIGURE 6 is a section of the tape feed gate taken on the line 6-6 of FIGURE 5; and

FIGURE 7 is a chart illustrating the relative time of operation of the several components parts.

To still further clarify the following specification, the operations are described in order of sequence of opera tion.

The tape guide gate It? (FIGURES 5 and 6) is held down by the latch 12 and spring 14. When the upward projecting trigger I6 of the latch 12 is manually pushed to the left (FIGURE 6) the guide gate 16, which is pivotally mounted on a shaft 17 on a ixed bracket 18 on the top cover plate 19 of the transmitter, will swing up clockwise as viewed in FIGURE 6 due to the biasing action of a coil spring 20 (FIGURE 5). With the gate 10 up, a tape 22 (FIGURE 2) provided with a longitudi nai row of feed holes may be positioned within the longitudinally extending channel 21 of plate 19 with certain of its feed holes engaged by the teeth 23 on a feed claw 2d. The subsequent closing and latching of the gate 1l) will hold the tape in place ready for transmission. A guide 26 (FIGURE 5), which is pivoted on the bracket 1d, may be swung to a position in which it rests in a groove 2S in the surface of the tape guide plate 19 to adapt the tape feeding device to accommodate a narrower l/lt; inch tape. In this manner, the tape feed is adapted to feed either a wide chad tape on which printing is performed along one edge of the tape or a narrow chadless tape on which printing is performed over the lidded apertures. The cover plate 3G (FIGURE l) forms an extension of plate 1g.

When a switch (not shown) is turned on, the transmitter will operate as the presence of tape 22 in the gate is eifective to depress the end of a lever 32 (FIGURES l, 2 and 6) which controls a switch in the circuit to the magnet 34 which controls the cam shaft start-stop operation. Having reference to FIGURE 2, the electromagnet 34 is supported by a bracket 35 to the rear mounting plate 36 of the unit and is electrically connected to a local power source through an appropriate control circuit. It is normally energized when the main power switch is closed and holds the armature 38 pivoted at 40, in its attracted position. Armature 38 is normally biased from its attracted position by a tensioning spring 42 which has one end secured to the armature 38 and its other end to a post 43. Armature adjusting screws 44 and 46 have screw threaded engagement with ears 4S and 47, respectively, of the mounting plate 36, to limit the extent of movement of the armature 38. When in its unoperated position, the knife edge 4S of a strip 49 secured to armature 38 engages a shoulder 5t) at the left end of a cam shaft stop lever 51 which is pivoted at its right end of a post 52 secured to the mounting plate 36. Near the center of the stop lever 51 is a stop 54 which co-acts with either of the lugs 56 on the end of the selector cam drum 58 to prevent the rotation of the drum 58 when the magnet 34 is not energized and the unit is at rest. The camshaft 60 is journalled in the mounting plate 36 and is connected through the usual .friction clutch to a constantly rotating power drive shaft which is suitably journalled in a frame and connected to the drive shaft of a motor.

FIGURE l shows a general view of the selecting mechanism and tape sensing levers which will now be described. The group of five sensing levers 62-70, one of which isshown in detail in FIGURE 3, have at their right ends sensing pins 72 adapted to engage code holes of the tape 22. These sensing levers 62, 64, 66, 68 and 3 70 are pivoted on a common support shaft 74 secured to the rear mounting plate 36 of the unit. The cornmon pivot axis of levers 62, 64, 66, 68 and '70 is parallel to the axis of camshaft 6).

The sensing levers 62--70 each control one of a set of transmitter selector levers 76, 7S, 86, 82 and 84, sensing levers 62, 64, 66, 68 and 70 controlling selector levers 76, 78, 8d, 82 and 3d respectively. Each sensing lever is provided with a hooked lug 86 (FIGURE 3) at its lower end which is moved into and out or position below the hooked end 88 of the corresponding selector lever as its pin enters or does not enter a code hole in the tape. This movement will block or unblock the lever and thereby determine the subsequent movement imparted to it by the cam with which it is associated as will be explained later. A bracket 90 (FIGURES l and 2) which is suitably secured to mounting plate 36, is provided with a forwardly projecting comb portion 92 for supporting and guiding the sensing levers 62-76 in mutually spaced relation. The cam drum 58, secured to the camshaft 66 is provided with a series of axially spaced cam sections the lobes of which are arranged helically around the drum to effect sequential engagement and operation of the selector levers. In the particular embodiment of the invention herein disclosed, seven selector levers 'I6-'73- 80-82-84--94-96 are provided, one 96, for the start impulse, five 76--84 for the code impulses, and one 94 for the stop impulse. The cam drum d includes a cam section for each of the seven selector levers and three additional cam sections for purposes hereinafter described. Each of the cam sections has a pair of diametrically opposed raised portions, or cam lobes which,

due to the helical arrangement of the cam sections on the cam durm 58, successively engage their associated mechanism once during each one-half, revolution of the cam drum 58. This in turn permits the transmission of code signals for two characters during each .revolution of the cam drum.

Each of the seven selector levers, one of which is shown in detail in FIGURE 3, has depending portions S1 and S3 adjacent its opposite ends, a cam follower S5, and a notch 87, which fits around a squared shoe S9 loosely held on the pivot post 91. A spring 93 is secured between a post and the lever 8i) to normally hold the lever against the shoe 89 at one end and a stop on the comb member 92 at the other end. By this construction, the selecting levers are each mounted for pivotal and radial sliding movement relative to pivot post 91,

The depending portions S1 and 83 of the selector levers engage and position a contact bail 93 (FIGURE 4) pivoted at 169 and having a pair of movable contacts 192') and 104 which are connected to the telegraph line by a V-shaped spring 106. A pair of stationary contacts 193 and 105 (FIGURES l and 4) cooperate with contacts 102 and 104 respectively to control the condition of the line circuit of the associated telegraph system. Contacts 103 and 105 are mounted in Contact supports 19S and 110 which are adjustable screws engaging terminals iitted into a supporting block 112 formed of insulating material. The contacts 1633 and 105 are plungers which are pressed upward by coil springs within the supports 10S and 110. The contact bail 98 is engaged near its ends by the depending portions 81 and 83 of the selector levers 8l) with just sumcicnt clearance to permit the levers and contact bail to pivot without excessive lost motion.

In the embodiment of the invention shown herein, there are provided two sets of contacts to permit use in a telegraph system of the polarized current type as well as one of the neutral, or current and no current, type which would utilize only one set of contacts. The contact bail 98 is of sulicient width to be operated in turn by each of the seven selector levers '76, '78, Si?, 82 and 84, which are capable of pivotable motion in either of two oppositely directed paths under the control of the sensing levers and cam drum to determine which contacts will be engaged, as well as by levers 94 and 98. Thus, if a sensing lever 7i) (FIGURE 3) blocks the end 88 of its associated selector lever 80, as the latter is engaged by its cam lobe the opposite end will move radially of post 91 on the squared shoe S9 so that depending portion 83 will abut bail 98 to engage contacts 104 and 105. If the sensing lever '70 does not block the end of the selector lever Si), the selector lever 8) will pivot with the shoe 9 upon the post 91 and drop the depending end portion 31 to abut the bail 93 and close contacts 102 and Attached to the rear of the sam drum S8 are two diametrically opposite lugs 56 (FIGURE 2) which cooperate with the stop lever 51 as hereinabove described; the first cam section 113 (starting from the rear) operates the sensing lever lifting bail 114 (FIGURE 3); the second cam section 11S (FIGURE 2) raises and lowers the tape feed claw lever 116; the third and fourth operate code selector levers 76 and 78; the fifth 117 operates the tape feed retracting lever 118; the sixth, seventh and eighth operate code selector levers 80, S2 and 84; the ninth cam controls the stop selector lever 94 and tenth cam controls the start selector lever 96. The timed sequence of operation of these cams is illustrated in FIGURE 7 and will now be described in detail.

The rst movement of the cam drum 5S following the unlatching by the dropping of the locking lever 51, causes the cam follower of the stop selector lever 94 (FIG- URE l) to drop off the cam lobe 119 and immediately thereafter the adjacent lobe 120 of the start cam engages the cam follower 35 of the start selector lever 96 and, as there is no blocking member provided for the start selector lever 96, the cam lobe will press down on the lever 96 and cause it to pivot on post 91 to lower its left end to cause depending portion S1 thereon to press the contact bail 98 downwardly which will open contacts 1M- and 165 and thereby place the associated telegraph line in a start (no-current) condition.

As the cam drum 5d thereafter continues to rotate, the depending cam follower arm integral with sensing lever lift bail 114 (FIGURE 3) drops off the lobe of the first cam section 113 and pivots in a counterclockwise direction as viewed in FIGURE 3. This movement of bail 114 releases the sensing levers 62, 64, 66, 68 and '70, which are individually spring biased in a counterclock- Wise direction about support shaft 74- as viewed in FG- URES l and 3, to permit their right hand ends carrying the tape sensing pins 72 to rise to a position in which the pin 72 abuts the tape in the event that there is no aligned perforation in the tape or in which the pin '72 passes through an aligned perforation in the tape in thc event that there is such an aligned perforation.

Further rotation of the cam drum 58 causes its lobe to press down on the projection 85 of the number l selector lever 76 to control the position of the contact baii 98 in accordance with the blocked or unblocked condition of the sensing lever 62. Following the movement ofthe #l selector lever 76, the cam lobe 121 of cam section 115 (FIGURE 2), the first of the two that are assigned to the tape feeding mechanism, detlects the follower 122 on the lever 116 to the right. The lever 116 is pivotally mounted on the post 126 which is in turn mounted on the rear mounting plate 36 of the unit. A leftwardly extending arm 128 of the lever 116 carries at its end a pin 130 which pivots and slides in a slot 132 in a depending portion of the tape feed claw 24. The complete lever 116 is normally biased in a clockwise direction about pivot post 126 by a spring 133 attached to an ear of the lever 116 and to a part of the frame 36. The extreme left end of the tape feed claw 24 also has a slot through which is slidably received the shaft 74 fixed to the frame 36 which allows the tape feed claw to pivot and/ or slide in a vertical plane. Carried at the right end of the tape feed claw 24 are the three pins or teeth 23 arranged in longitudinal alignment to engage three adjacent feed holes in entente the tape 22. the lever 116 in a counterclockwise direction about the post 126 thus dropping its arm 128. The pin 13() will pull down on the claw 24 and, as its left end is held against downward or leftward movement by its pivotal connection to shaft 74, cause claw 24 to pivot in a clockwise direction thus disengaging the pins 23 from the tape feed holes.

Further rotation of cam drum S causes a lobe to press down on #2 selector lever 78 in the same manner as previously described for the #l selector lever '76. Still rotating in a clockwise direction as viewed in FIGURE 2, the cam drum 58 now brings the cam lobe 13S (FIGURE 2) in contact with the follower 142 in the middle of the claw retracting lever 11S. The claw retracting lever 11S is pivoed on the post 52 and has an upwardly extending arm which has a turned over shoulder 144 which engages the right edge 14S of the depending portion of the tape feed claw 24. The claw retracting lever 118 is biased in a counterclockwise direction by a spring 145. As the follower 142 rides up on the cam lobe 138, it moves the lever 118 to the right to allow the feed claw 24 to move to the right through the pull of a spring 147. The pins 23 of the feed claw 24 are now directly underneath the next adjacent set of three feed holes, that is, a set of three feed holes including two of the previously engaged set and one new feed hole. Further rotation of cam drum 58 brings #3, 4, and 5 selector camspinto play to actuate selector levers 30, 82 and S4 in sequence. During the movement of the #4 selector lever 32, the follower 122 on the lever 116 which imparts the up and down motion to the feed claw 24, rides down its cam lobe 121'. The feed claw 24 will then rise into engagement with the aligned set of feed holes in the tape due to the upthrust imparted through pin 13G by the clockwise movement of the lever 116. Immediately after the #5 selector lever 84 has operated the Contact bail 98, the follower arm on the sensing lever lift bail 114 rides upon the cam lobe of cam section 113 diametrically opposed to the lobe from which it dropped upon initiation of operation and the associated bail 114 pivots the live sensing levers in a clockwise direction in opposition to their biasing springs to disengage pins 72 from the code holes of the tape 22. This operation is simultaneous with the engagement of the #6 selector lever 94 with its cam to pivot the contact bail 98 for a stopping impulse. Further rotation causes the follower 1.42 on the retracting lever 11S to drop off an abrupt shoulder of the cam lobe 13S which causes its upper end to be jerked to the left by the spring 146. As the shoulder 144 at its upper end is in engagement with the edge 145 of the depending portion of the feed claw 24 and as the spring 146 overpowers the spring 147, the feed claw 24 is jerked to the left. The tape is thus pulled one character space to the left. As can be seen from the above description of the feed claw mechanism, its movement follows a substantially rectangular pattern, consisting of two rectilinear movements joined by two pivotal movements. lf the magnet armature 38 has moved to the right due to its magnet 34 becoming de-energized, the lug 56 will engage the latch S4 and the cam drum S8 will be held from turning through slipping of the clutch connecting it to the motor drive shaft.

Three actions can cause the magnet 3d to become de-energized: In series with it and a local source of electrical power are an olf-on switch, a tight tape switch 150 (FIGURE 2) and a tape out switch 156. The olf-on switch is a toggle which allows the tape transmitter to be stopped manually at any time without turning off the driving motor. The tight-tape switch 15G operates by the lifting of the arm 148. The end 149 of the arm 148 is bent to hold a loop of tape which if pulled tight due to stopping of the supply source will raise the arm 14S thus opening switch 150 and breaking the magnet circuit. Another switch 156 operates from the lever 32 the end of which projects through an opening in the feed guide Movement of the follower 122 will turn.

plate 19. Presence of tape in the gate 1li depresses the lever 32 holding the switch 156 and magnet circuit closed.

It is desirable to be able to disengage the feed claw 24 from the message tape when the transmitter is in its stopped condition to enable an attendant to feed a tape into the gate without lifting the gate 10, also it is advantageous to be able to move the tape forward or backward without unfastening the gate lil. The structure by which this is accomplished will now be described. The feed claw 24 (FIGURES l and 2) has an upwardly projecting rounded portion 166` which passes through slot 162 in the tape guide plates 19 and 30. When the transmitter is idle, the feed claw 24 is in engagement with the tape 22 making it impossible to move the tape without tearing the feed holes. An attendant may press on the tape at the point where it passes over the projecting portion 161i of the feed claw 24 which action will depress the feed claw 24 thus disengaging the tape. He may then push the tape forward or backward with short strokes on the projecting rounded portion 16) until the desired amount of tape has been backed up or pulled through. In starting a tape into the transmitter the attendant has only to press on the projection 16d which lowers the claw 24 and while holding the projection ldown feed the tape under the gate 1lb far enough to place the first feed hole of the tape over one of the teeth 23 oil the feed claw 24. Subsequent release of the projection loll will allow the claw to rise and engage the feed hole to start the tape moving as soon as the transmitter is turned on. Should it become necessary to stop the tape at any time while the transmitter is operating this may be done by pressure on the tape above the projection 16d. The tape will thus be held from moving and the feed claw lever will reciprocate in its retracted position.

The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiment is therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

What is claimed and desired to be secured by United States Letters Patent is:

l. A perforated tape controlled transmitting mechanisrn comprising a fixed transmitting contact, a bail having av contact thereon and mounted for pivotal movement between a first position of engagement of said bail contact with said fixed contact and a second position of disengagement of said contacts, a set of bail operating levers disposed on the side of said bail opposite -said fixed contact and each lever mounted at one end for pivotal and radial sliding movement relative to a common axis spaced from and parallel to the pivot axis of said bail, a set of blocking latches permutatively settable to operative and inoperative positions, said latches when in their operative positions being effective to engage the free end of one of said operating levers, a perforated tape sensing element individual to each of said latches Aand operative to control the position thereof, and a rotatable cam member provided with offset projections on the periphery thereof operative upon rotation of said member to engage said levers sequentially intermediate their ends to impart pivotal movement about said common axis to each lever unrestrained by a blocking latch and pivotal movement about the normally free end of each lever restrained by a blocking latch so that said levers sequentially control the position of said bail to variably engage and disengage said contacts in accordance with permutative setting of said latches.

2. A perforated tape controlled transmitting mechanism comprising a pair of fixed transmitting contacts, a bail having a pair of contacts thereon and mounted for pivotal movement between a first position of engagement of one of said bail contacts with one of said fixed con- 'i' tacts and a second position of engagement of the other of said bail contacts with the other of said iixed contacts, a set of bail operating levers disposed on the side of said bail opposite said fixed contacts and each lever mounted at one end for pivotal and radial sliding movement relative to a common axis spaced from and parallel to the pivot axis of said bail, a set of blocking latches permutatively settable to operative and inoperative positions, each of said latches when in its operative position being effective to engage the free end of one of said operating levers, a tape sensing element individual to each of said blocking latches and operative to control the position thereof, and a rotatable cam member provided with offset projections on the periphery thereof operative upon rotation of said member to engage said levers intermediate their ends to impart pivotal movement about said cornmon axis to each lever unrestrained by a blocking latch and pivotal movement about the normally free end of each lever restrained by a blocking latch so that said levers sequentially control the position of said bail to variably engage said contacts in accordance with the permutative setting of said latches.

3. A perforated tape controlled telegraph transmitter comprising a set of permutatively settable blocking members eacn operable to one or two alternative positions indicative of a signal to be transmitted, a tape sensing element individual to each of said blocking members and operative to control the alternative positioning thereof depending upon the presence or absence of a perforation in a tape being sensed, a set of contact operating levers each normally pivotally mounted adjacent one end and each adapted to pivotally coact at its other end with an aligned one of said pivoted blocking members when in one of said alternative positions to be restrained against pivotal movement about said one end, a pair of transmitting contacts common to all of said contact operating levers and a rotatable cam member operative to engage said levers intermediate their ends and to sequentially pivot each of said contact operating levers about one of its ends in accordance with the variable positions of said blocking members to variably operate the pair of said contacts according to the signal to be transmitted.

4. ln a perforated tape controlled telegraph transmitter, an independently rotatable member, a series of contact operating levers each having twov alternatively selectable oppositely directed paths of motion, a pair of controlling contacts common to said series of said contact operating levers, means operable by said rotatable member to sequentially actuate said contact operating levers in one of their said paths of motion, permutatively settable means for restraining the movement of a selected group of said operating levers in said first path of motion to compel the movement thereof in a second path of motion, and perforated tape sensing means for controlling the permutative setting of saidpermutatively settable means whereby said pair of contacts is actuated in a predetermined manner to correspond to the perforations` sensed in a perforated tape by said tape sensing means.

5. A perforated tape controlled transmitting mechanism comprising: a xed transmitting contact; a bail having a contact thereon and mounted for pivotal movement between a iirst position of engagement of said bail contact with said fixed contact and a second position of disengagement of said contacts, means for pivoting said bail to one or the other of said two positions to cause a successive combination of contact engagements and/or disengagements comprising a set of bail operating levers disposed on the side of said bail opposite said iixed contact and each lever mounted at one end for pivotal and radial sliding movement relative to a common axis spaced from and parallel to the pivot axis of said bail and adapted during at least one of said movements to move said bail to engage said contacts, a set of blocking latches permutatively settable to operative and inoperative positions, said latches when in their operative positions being effective to engage the free end of an associated one of said operating levers, a perforated tape sensing elementv individual to each of said latches and operative to control the position thereof, and a rotatable cam member provided with oiiset projections on the periphery thereof operative upon rotation of said member to engage said levers sequentially intermediate their ends to impart pivotal movement about said common axis to each lever unrestrained by a blocking latch and pivotal movement about the normally free end of each lever restrained by a blocking latch so that said levers sequentially control the position of said bail to enable variable engagement and disengagement of said contacts in accordance with permutative setting of said latches.

6. A perforated tape controlled transmitting mechanism comprising: at least a pair of transmitting contacts; a bail having one of said pair of contacts thereon and mounted for pivotal movement between a first position of engagement of said bail contact with the other fixed contact of said pair and a second position of disengagement of said bail contacts with the other of said pair of contacts, means for moving said bail to positions of contact engagement and of contact disengagement comprising a set of bail operating levers disposed on one side of said bail and each lever mounted on one end for pivotal and radial sliding movement relative to a common axis spaced from and parallel to the pivot axis of said bail, at least one of said movements of said bail operating levers enabling engagement of the lever with sai'l bail to assure positioning of said bail in a contact engaging position, a set of blocking latches permutatively settable to operative and inoperative positions, each of saidV latches when in its operative position being effective to engage the free end of one of said operating levers, a tape sensing element individual to each of said blocking latches and operative to control the position thereof, and a rotatable cam member provided with offset projections on the periphery thereof operative upon rotation of said member to engage said levers intermediate their ends to impart pivotal movement about said common axis to each lever unrestrained by a blocking latch and pivotal movement about the normally free end of each lever restrained by a blocking latch so that said levers sequentially control the position of said bail to enable variable engagement of said contacts in accordance with the permutative setting of said latches.

References Cited in the tile of this patent UNITED STATES PATENTS 1,994,949 Huebner et al Mar. 19, 1935 2,331,914 Janiszewski Oct. 19, 1943 2,372,515 Potts Mar. 27, 1945 

